The present invention relates to a connection device for fluid circuits shiftable between a first operating position, in which it allows hydraulic connection of two adjacent sections of the circuit, and a second operating position, in which it allows disconnection of the two adjacent sections of the circuit without causing fluid losses from the circuit, wherein the operation of connecting and disconnecting the two circuit sections can be carried out under load, i.e. with at least one of the two circuit sections containing fluid under pressure.
A connection device for fluid circuits according to the preamble of the accompanying independent claim 1 is known from U.S. Pat. No. 3,291,152.
Connection devices for fluid circuits of the type mentioned above are commonly known by the acronym SSQD (“Self-Sealing Quick Disconnect”). The known SSQD devices typically use mechanical springs to ensure that a closure member is closed during the disconnection operation, thereby preventing loss of the fluid to the outside from the two circuit sections to be disconnected. These known devices have a number of disadvantages, including first of all that, as soon as the two circuit sections have been connected, they generate a pressure wave (the so-called “fluid hammer”) which propagates within the circuit. In order to avoid the risk that the pressure wave may damage components of the circuit which are particularly sensitive to overpressure conditions, it is necessary to adopt suitable measures, for example installing an accumulator arranged to absorb the pressure peaks within the circuit. Furthermore, the known connection devices are heavy and bulky, as well as structurally complex and therefore also particularly expensive, to such an extent that they are used exclusively in very specific applications, for example in the space industry.
US 2015/0114607 discloses a dual-phase fluid circuit, comprising an evaporator device arranged to receive heat from a hot body, a condenser device arranged to transmit heat to a cold body, a first conduit through which a working fluid, in vapour phase, flows from the evaporator device to the condenser device, and a second conduit through which the working fluid, in liquid phase, flows from the condenser device to the evaporator device. The circuit further comprises a pair of first thermal expansion valves, which are placed upstream and downstream of the condenser device, respectively, and are configured to prevent or allow the flow of the working fluid within the circuit depending on the temperature of the working fluid through the condenser device, as well as a pair of second thermal expansion valves, which are placed upstream and downstream of the evaporator device, respectively, and are configured to prevent or allow the flow of the working fluid within the circuit depending on the temperature of the working fluid through the evaporator device. When the two first (and/or the two second) thermal expansion valves are in the closed position, it is possible to disassemble the circuit section interposed between said valves, for example to replace the condenser device (and/or the evaporator device), without having to empty the entire circuit. According to this known solution, however, the disconnection of the two first (or of the two second) valves from the circuit section interposed therebetween causes the loss of the working fluid contained in said circuit section, which has to be avoided in the case where the working fluid is a hazardous fluid, for example a toxic, reactive or very hot fluid. This known solution is therefore not able to allow for the disconnection of two adjacent circuit sections without causing fluid loss from the circuit.